As is well-known, since propylene polymers are excellent in moldability, as well as having satisfactory characteristics such as mechanical properties, heat resistance, solvent resistance, oil resistance and chemical resistance, they have generally been produced industrially and utilized in various fields such as parts for automobiles, electrical and electronic instruments, as well as daily necessities. However, since they have no polar groups in the molecules (i.e., "non-polarity") and are extremely poorly soluble in most organic solvents, they are extremely poor in adhesion properties with various adhesives (adhesive materials). Consequently, they have various disadvantages, as is illustrated by door linings interior materials for automobiles.
Door linings are usually made of polyvinyl chloride leathers, which are laminated with polypropylene foam, polyethylene foam, polyurethane foam, etc. However, since the polyvinyl chloride leathers are poor in rigidity, they can not be used as they are, but are bonded by means of adhesives with molding products of acrylonitrile-butadiene-styrene terpolymer resin (ABS resin) or resin boards of polypropylene blended with filler such as wood powder as a substance for increasing the rigidity of the lining material.
However, with the recent trend of the reduction of weight and cost in automobiles, polypropylene resins (propylene polymers), which are inexpensive and have satisfactory moldability, have been used increasingly in place of the ABS resin or the filler-containing polypropylene resin.
However, since the propylene polymers have no polar groups in the molecule and are high molecular materials that are extremely inert chemically, polyvinyl chloride leathers are actually bonded by means of adhesives coated to molding products (door liner substances) after previously applying a primer bondable with the propylene polymer or after applying a pre-treatment such as plasma treatment, corona discharge treatment and UV-ray irradiation. Accordingly, production is time consuming and increases the cost.
Upon preparing linings of other automobile interior materials, for example, instrument panels, pillars, ceiling materials, armrests, etc., there are similar problems when using propylene polymer and bonding polyvinyl chloride leather.
Recently, U.S. Pat. No.4,735,988 has disclosed that a propylene polymer composition containing a modified propylene polymer treated wth an organic compound having unsaturated bonds and hydroxyl groups and an organic peroxide has satisfactory adhesion to polyurethane without using a primer. However, the bondability of the propylene polymer composition with two-component system polychloroprene adhesives or two-component system chlorinated polypropylene adhesives is insufficient and there are keenly been demanded a propylene polymer composition showing improved adhesion with these adhesives even without using a primer.